At gasoline service stations and other facilities that dispense fuel, underground tanks are commonly installed for storage of the fuel. A submersible electric pump operates to pump the fuel through a vertical column pipe when the dispenser is activated. The fuel is then delivered to a dispensing line which extends to a dispenser having a nozzle that discharges the fuel under the control of the service station attendant or customer.
The fuel path includes an interface between the column pipe and the dispensing line. Electrical power must also be supplied to the submersible pump from a power source which may be located in a building or other area. Conventionally, an assembly referred to as a packer or a manifold forms the interface section of the flow path and also allows electrical lines to extend through the column pipe in an electrical conduit leading to the pump.
The packer/manifold assemblies that have been used in the past have not been altogether without problems. Any fuel that leaks from the piping should be contained, and packers have not always been able to provide satisfactory containment. Consequently, leaking fuel can contaminate the area and can create environmental problems and violations of regulatory laws. Excess vapor pressure from the fuel can also cause similar problems.
The packer assembly is normally equipped with a check valve which holds the line pressure to the dispenser in order to assure that fuel is immediately available for each dispensing cycle. Proper maintenance procedures require that the check valve be inspected and serviced at suitable intervals. Often, it is necessary to disassemble and reassemble a number of components in order to obtain access for removal of the check valve. The complexity of this procedure adds to the maintenance costs and the down time of the equipment.
The column pipe and pump must also be removed and serviced periodically. Again, this can be a complicated procedure because the components of the packer assembly between the column pipe and the check valve must be disconnected and then reconnected after maintenance operations have been completed. Tools are required for assembly and disassembly of the components, and this adds both to the cost of the maintenance and to the time the system is out of service.